I was looking through the google patents page and found an interesting graph.
http://www.google.com/patents?id=bfU...=2008#PPA64,M1
It is on page three, and it is the first time that I have seen some general surge guidlines outside of what is on the left side of the map. I don't know if this will be more or less useful, but I found it interesting anyway.
ETA: it looks like when I click my link it takes me right to the chart.